Poultry Industry Association executive director Mike Brooks said they were as rare as hens' teeth and were something he had heard of but never seen.
Hen's teeth are though to be an evolutionary throw back, genes long since deactivated that in the distant reptilian past of the birds gave them teeth, becomming accidentally re-activated today.
Unfortunately, this particular case doesn't seem to be a throwback to the days when they had fully functional 'hands', rather than wings. It looks like it has four legs and still has two wings, and, as noted, they think its a matter of the leg stem cells spliting too much. Still, pretty fascinating.
Evolution of avian wing diagram
